This invention relates generally to internal pipe lining rehabilitation devices or systems, and more specifically relates to lining systems that are adapted and adaptable for use in the structural repair or remediation of degraded, damaged or leaking pipes, or such lining systems adapted and adaptable to improve or upgrade qualities and characteristics of pipes prior to or after use or installation. Even more specifically, this invention relates to lining systems that spray a lining onto the internal pipe surface for rehabilitation or remediation of an existing host pipe.
Lining devices for pipe rehabilitation that spray a liner onto the internal surface of a pipe in need of repair whereupon the liner cures to form a “pipe-within-a-pipe”, are typically referred to by the acronym SIPP, which stands for Spray-In-Place-Pipe. Pipe rehabilitation rather than pipe replacement is practiced heavily in industrial and municipal water markets due to two primary advantages. Firstly, the cost of pipe rehabilitation is significantly cheaper than pipe replacement. Secondly, pipe rehabilitation is far less of an invasive practice than replacement. For instance, replacing a pipeline running under a major road or building results in a major disruption to a community and in some cases, is not a feasible solution. Thus, pipe rehabilitation methods are a highly valued solution and far more desirable in many situations.
Structural (i.e., self-defined, stand-alone or self-sustaining) linings installed by polymeric spray or SIPP devices for piping systems are currently without an industry installation standard. The difficulty in setting design standards arises because of the many different types of lining faults, such as ringing, puddling, thickness inconsistencies, and lining voids, which result from current rehabilitation methods. These lining faults are a direct result of the past manufacturers inability to overcome the mechanical function insufficiencies of the SIPP or similar equipment that are the direct causation of these faults.
The common SIPP devices utilize an accumulator reel to retract an umbilical or tether tensile member (the term “umbilical” being used hereafter to refer collectively to an umbilical, tether, tension member or similar tensile structure or combination of such members, and containing or further comprising material, electrical and communication transmission members) which is attached to the spraying device as it sprays the liner onto the inner pipe wall. Accumulator reel torque is transmitted by the umbilical member into a tensile load on the sprayer device. These SIPP devices produce a liner that is unpredictable in thickness due to what is known as “stick-slip” phenomenon—the changing resistive force during the application process due to the capstan effect from variations in pipe geometry (i.e., friction on the umbilical member due to pipe bends and turns), elasticity of the umbilical member, drag on the umbilical member resulting from droop or sag due to the extended length of the umbilical member, and sprayer head positioning. When the spraying apparatus sticks, it slows or stops momentarily and excessive liner forming material is sprayed onto the pipe over a short distance, resulting in a liner that is too thick over this segment. When the spraying apparatus then unsticks, i.e., slips, it moves forward too rapidly, resulting in segments where the liner is too thin. These inconsistencies are typically visibly obvious and are commonly referred to as the ringing effect or more simply “ringing”. The ringing effect compromises the structural integrity and hydraulic capacities of the liner.
There are three main elements in the common SIPP system: a spraying or lining apparatus, an umbilical member, and an accumulator reel. The spraying function is performed by a mechanism that dispenses, propels or otherwise distributes uncured liner material, such as for example a polymer resin, onto the inner surface of the pipe. The liner material then cures in place to form a structural liner or lining—i.e., a new internal layer or pipe within the original pipe. The umbilical member contains conduits that convey the liner material from a pumping source to the sprayer apparatus and houses any electrical wires needed to send power and communicative signals between elements of the SIPP system within the pipe and external to the pipe. Additionally, the umbilical member houses a separate, or comprises as a whole, a tension member extending between the accumulator reel and the spraying device, such that the umbilical member pulls the sprayer apparatus through the pipe. The accumulator reel is a reel that houses, deploys, and accumulates the umbilical member.
Almost all current SIPP lining devices are static, non-self-propelled units, also referred to as Pull-Through (PT) technology or devices. PT technology is an appropriate term due to the mechanical means by which the devices are driven during the lining process. PT devices are pulled through the pipe by an external driving mechanism, most commonly a powered accumulator reel or winch. These lining devices are mounted on skids, wheels or rollers which help reduce the frictional drag between device and pipe wall.
Due to gravitational forces and its extended length, the umbilical member will usually sag and make contact with the bottom of a pipe, resulting in increased friction and drag. The tensile load exerted by the accumulator reel is a result of friction between the umbilical member and the pipe wall, and/or the spraying apparatus and pipe wall. The second frictional force is constant since it is rigid and has nearly a fixed contact area with the pipe wall. The first and most significant frictional force is the friction on the umbilical member. For a straight pipe, the tensile load required has a linear relationship, increasing linearly with increasing lining distance. Sagging of the umbilical member directly affects the tensile load. When bends are present in the pipe the tensile load must additionally account for the capstan effect that increases exponentially proportional to the summation of the total contact wrap angle between umbilical member and the pipe wall.
Some SIPP systems have recently attempted to diminish lining faults by providing a self-propelled spraying apparatus. While this does have some effect on the consistency of the lining, the system is still erratic in liner application due to the lack of controlled velocity of the umbilical member itself. The mass of the umbilical member in conjunction with the surface contact area has dramatically more influence on the consistency of a liner than does the ability to control the propulsion of the small spraying apparatus alone. A self-propelled lining device has no mitigating effect regarding the capstan effect or nonlinear friction imparted on the umbilical member. It should also be noted that a self-propelled spraying apparatus cannot provide the required force to pull an umbilical member of significant length (e.g., greater than 150 feet) into the pipe. Even with a self-propelled spraying apparatus the umbilical member still requires that the umbilical member be winched down through the pipe to the starting point.
To address these problems and provide a pipe liner with consistent thickness, it is an object of this invention to provide a self-propelled SIPP or similar type internal pipe lining system that comprises multiple propulsion devices, with one propulsion device being directly associated with the sprayer apparatus such that the sprayer apparatus is essentially self-propelled, and with the remaining plurality of propulsion devices being associated with the umbilical member at spaced intervals, thereby enabling the use of longer umbilical members. In this manner, the internal pipe lining system is essentially self-propelled for both insertion and retraction during the lining operation, such that little to no retraction force need be applied by the accumulator reel. It is a further object to provide the umbilical member propulsion devices as modular units capable of rapid attachment and detachment from the umbilical member, thereby enabling the propulsion devices to be quickly removed from the umbilical member during the rewind operation.